In the related art, spectral measurement methods have been employed as methods for analyzing components of specimens such as tissue slices (for example, see Non-Patent Literatures 1 and 2). Raman scattered light coming from individual positions of a specimen is detected, Raman spectra are acquired by diffracting the detected Raman scattered light, and scalar values related to components at the individual positions of the specimen are obtained by performing principal component analysis on a collection of the acquired Raman spectra.
The acquired Raman spectra include components derived from various types of noise, such as scattered light coming from the slide glass on which the specimen is placed, autofluorescence of an optical element, thermal noise of a detector, and so forth. Principal component analysis has also effectively been utilized in processing for removing these noise-derived components from the acquired Raman spectra. Specifically, higher-order principal components are removed, assuming that the higher-order principal components obtained by means of principal component analysis are components derived from noise, and Raman spectra are reconstructed by using only lower-order principal components.